The present invention refers to a device especially for osteodistraction, that comprises means for anchoring to various bone parts, that are separate from one another or have been separated by sectioning, and that are bound together by mechanical means for holding the latter in a pre-set relative position and/or by the simultaneous pressure for the distancing or bring-together of these bone parts.
Osteodistraction operations have as their purpose to stretch the bone, causing the formation of new bone tissue. To that end, the apparatuses for osteodistraction must be fastened, distant from each other, to bone zones that have first been separated, permitting the slight growth of the bone. Such an operation presents the advantage that it can be carried out as simple ambulatory operation, with local anaesthesia and without requiring the taking of any bone from the iliac crest, i.e., without risks.
At present, osteodistraction proves advantageous in cases of malformation and of orthopedic problems. A particular application is for the problems of nocturnal snorers, especially those subject to infarcts in sleep, and of tumor patients.
Presently, even though the technique is of course ambulatory, the devices and apparatuses for osteodistraction on the market are very bulky and especially traumatic. Some of the night devices are obtained, for some applications, in the form of an external device and therefore it is cumbersome from the standpoint of ambulatory treatment as well as from that of convenience and for its psychological effect on the patient.
Night devices have, in their simplest form, two fastening elements that are connected together by a spreading-apart/bringing-together endless screw/nut device, or a pinion and rack device. Screw/nut or pinion/rack devices generally exert forces that vary from 4.5 to 9 kilograms. Such forces are appreciable and they exert a considerable pressure on the temporal mandibular articulation with effects that are not always foreseen.
A further limitation of the present devices results from the fact that they cannot operate vertically or in any case in compression, i.e., in such manner as to close spaces.
The purpose of the present invention is to obtain devices for osteodistraction operations with which it is possible to obviate the drawbacks of the night devices, permitting to obtain reduced sizes and weights, the exerting of distraction with more moderate forces and in a physiological manner that agrees better with the body and especially with tissues and articulations. The apparatuses according to the invention must be of easy and economical construction, and they must guarantee maximal operational flexibility for the different applications required.
The invention achieves the above-mentioned goals with a device for osteodistraction in operations of the type described at the onset, in which at least two fastening elements to two bone parts separate from each other are engaged together in a displaceable manner along at least one pre-set direction, there being inserted between these elements means for a thrust in the distancing or in the direction of distancing or of traction, i.e., in the bringing-together direction.
According to an improvement, these elastic means are provided in combination with means for imparting different loads to the elastic elements.
Generally, the two fastening devices may each present at least one guiding element that engages slidingly with that of the other fastening device, for example cylindrical elements telescopically displaceable relative to each other, such as a cylindrical tubular element and a guiding wire or pin.
The elastic element is made up of a spring inserted between radial joining elements of the two guiding members engaged in a sliding manner, of which at least one is axially displaceable along said guiding member and blockable into position on that guiding member itself, in a removable manner.
Advantageously, in order to exert a given force, it is possible for each fastening element to provide a pair of parallel guiding elements that engage slidingly with a corresponding element of the other fastening member, it being possible to provide for an elastic member (i.e., a traction or thrust spring) on each guiding element executed substantially according to the above-description.
The means for the variable loading of the springs can be separate for each pair of telescopic guiding elements, or they can be provided connected among themselves, in such manner that they can load the springs either differently or in a similar manner.
To permit a pressure in the compression direction (i.e., for the bringing-together of the two fastening elements), one of the guiding elements associated with one of these fasteners has means for the lengthening of the joining parts that cooperates with the elastic means in a position intermediate between the other fastening means and the corresponding radial joining element of the spring.
According to an improvement, the two telescopic guiding elements, slidable relative to each other, or other equivalent guiding means are executed as a separate and pre-fabricated construction element, and are equipped with means for being coupled, fastened or anchored to the fastening elements. This may be done for both end fasteners at the ends of the pair of guides as well as for one only of these fasteners, while the other one is assembled as one piece or fixed with the corresponding end of the pair of guides.
The fastening elements, in turn, may be double or triple fasteners that permit fastening or affixing to them two or more guides with their related elastic means, along two or more directions to exert the thrust or compression in two or more different directions.
A particular fastener is made up of two opposite elements hinged together, and each one of them is configured to be affixed to a sliding guide of a thrust or compression unit. The hinge makes it possible to orient the two connected thrust or compression units, in succession, along different axes. The hinge shaft or pin may be fixed, relative to the compression or traction directions, perpendicular, for example. The hinge, however, may also be in the form of a spherical joint or articulation, permitting relative angular positioning between the two thrust or compression units along other directions in the space.
A particular form of execution provides elements for direct fastening to the bone, for example to the mandibular bone. In this case, in the version in which the fastening elements are separate from the thrust or compression unit or units, a type of removable hooking or fastening of these two parts from each other can be of the coupling type, the fastening element provided being a couplable element such as a pin or pivot, and the pressure unit being provided with an articulation seat such as a segment of a cylindrical tubular element or the like, or vice-versa, which two elements (i.e., the articulation pivot and the corresponding cylindrical tubular element) being oriented transversely to the direction in which the thrust or compression is exerted.
For other applications, the means for anchoring the osteodistraction unit or units are executed directly on the teeth. In this case, according to the invention, in order to permit physiologically correct displacements, especially with respect to the orientation of the teeth, the units are anchored to the fasteners by means of spherical coupling joints. The latter may be of the slip-hook type, or a simple free joint, and they are maintained in position by pressure forces of the thrust units, on the seats associated with the anchorings.
The spherical anchoring type, or the slip-hook type joints, with removable fixation, make it possible to obtain appreciable advantages by coupling. For example, in addition to the greater correctness of the distraction operation, relative to the physiological conditions, these devices, especially the different thrust or compression units, are easily removable whether as a combined unit or individually.
Thanks to the above-described units, it is possible to execute with great simplicity, and relatively economically and rapidly, an unlimited number of apparatuses for osteodistraction, that perfectly meet the requirements of the case and have an elastic action suited to the physiological requirements of the human body. These devices are very small, and they may be applied inside the oral cavity. They are light and exert forces that do not penetrate the bond structure nor the articulations. Furthermore, it being possible to vary the pressure of the elastic elements, when the growth of bone tissue has caused a displacement of the fastening elements themselves, by which the springs are unloaded, or when they exert insufficient pressure on the bone parts, it is possible to vary (i.e., to increase) the pressure of the springs to restore the distraction action. Over a certain range the pressures remain linear, without producing any peaks and not requiring too frequent adjustments.
Other improvements or variants of the invention constitute the object of the dependent claims.